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Breaker trips before pump starts

Ok, i hope someone can help because my wife is worried about the lawn (its turning brown). A couple of weeks ago i found out my pump was not working. It was just humming when turned on. I replaced it with a used one from my mom's uncle that swears this pump works. The problem i am having is when i try to activate a zone the breaker trips. I hear the relay click on. I have a 1 HP pump, 15amp breakers. Any help or any suggestions would be great!!! Thanks

It all depends on the motor - there are weenie-grade pumps sold at big-box stores that have wimpy motors that lack the power of 'standard' motors. You can look for the "service factor" on the label of the motor - the higher the number, the stronger the motor - any 1 HP motor with a standard power factor is likely to pop a 15 amp breaker.

If you want absolute certainty of powering any 1 hp pump, you need something better than 115 volts and a 15 amp breaker.

Well i don't understand then. What i have set up right now is the same set up i had a year ago and it worked just fine. I don't know what is different than before. I had a 1HP pump with 15amp breakers running to it.
What is new today; we switched out the breakers and the same issue accorded the breakers popped(15 amps breakers). We unhooked the wires to the pump and tried to kick on the pump to see if power was getting to the pump. When we did this the breakers popped again. I would assume the relay is bad, is this correct?

Are you sure the pump is wired properly. Many pumps can be wired 110 or 220.
At any rate, your pump is pulling too many amps, either because the motor is fried, or it's wired incorrectly.
I've seen faulty relays before, but I've never seen a faulty relay pop a breaker.

This post has been edited 1 times, last edit by "Central Irrigation" (May 28th 2012, 9:30am)

"I had a 15 amp breaker and a 1 HP pump" means nothing whatsoever. The very-good cast-iron jet pumps I use have no chance of working with the combination of 1 HP and 15 amp breaker, because the motor has a starting surge that will absolutely trip the breaker.

Note the breakers specified in the chart. Maybe it's time you upgraded the electrical supply to your sprinkler pump.